Immunoregulatory abnormalities have been shown to exist in a wide variety of "autoimmune" and chronic inflammatory diseases, including systemic lupus erythematosis, chronic rheumatoid arthritis, type 1 diabetes mellitus, inflammatory bowel disease, biliary cirrhosis, uveitis, multiple sclerosis and other disorders such as Chrons disease, ulcerative colitis, bullous pemphigoid, sarcoidosis, psoriasis, ichthyosis, and Graves ophthalmopathy. Although the underlying pathogenesis of each of these conditions may be quite different, they have in common the appearance of a variety of autoantibodies and self-reactive lymphocytes. Such self-reactivity may be due, in part, to a loss of the homeostatic controls under which the normal immune system operates.
Similarly, following a bone-marrow or an organ transplantation, the host lymphocytes recognize the foreign tissue antigens and begin to produce antibodies which lead to graft rejection.
One end result of an autoimmune or a rejection process is tissue destruction caused by inflammatory cells and the mediators they release. Antiinflammatory agents such as NSAID's and corticosteroids act principally by blocking the effect or secretion of these mediators but do nothing to modify the immunologic basis of the disease. On the other hand, cytotoxic agents such as cyclophosphamide act in such a nonspecific fashion that both the normal and autoimmune responses are shut off. Indeed, patients treated with such nonspecific immunosuppressive agents are as likely to succumb from infection as they are from their autoimmune disease.
Cyclosporin A which was licensed by the US FDA in 1983 is currently the leading drug used to prevent rejection of transplanted organs. The drug acts by inhibiting the body's immune system from mobilizing its vast arsenal of natural protecting agents to reject the transplant's foreign protein. Though cyclosporin A is effective in fighting transplant rejection, it is nephrotoxic and is known to cause several undesirable side effects including kidney failure, abnormal liver function and gastrointestinal discomfort.
Newer, safer drugs exhibiting less side effects are constantly being searched for in the field.
The 23-membered tricyclo-macrolide immunosuppressant, FK-506 (FR-900506), ##STR3## and related compounds which were isolated and characterized by Tanaka, Kuroda, and co-workers at Fujisawa Pharmaceutical Co. in Japan (see J. Am. Chem. Soc., 1987, 109, 5031, and U.S. Pat. No. 4,894,366 (issued Jan. 16, 1990)) have been shown to possess exceptional immunosuppressive activity. A Fujisawa United States patent (U.S. Pat. No. 4,929,611, issued May 29, 1990) discloses the use of FK-506-type compounds in treating resistance to transplantation. In particular, the compound FK-506 (FR-900506) has been reported to be 100 times more effective than cyclosporin in the supression of in vitro immune systems (J. Antibiotics 1987, 40, 1256). In addition, these compounds are reputed to possess topical activity in the treatment of inflammatory and hyperproliferative skin diseases and cutaneous manifestations of immunologically-mediated illnesses (EPO Pub. No. 0,315,978).
A Fisons European patent application (EPO Publication No. 0,323,042) discloses various derivatives of FK-506-type immunosuppressants related to the present application, such as 18-hydroxy FK-506, which are described as having immunosuppressive activity (as determined in Mixed Lymphocyte Reaction Tests and Graft Versus Host Assay). In contrast, the compounds of the present invention are antagonists and have the ability to block the activity of FK-506-type immunosuppressants.
As used herein the term "agonist" denotes ability to initiate or promote a particular drug activity. The term "antagonist" denotes the ability to block a particular drug activity.
Accordingly, an object of the present invention is to provide new analogs of these tricyclomacrolides which will (1) modify the restoration of the balance of the help-and-suppression mechanism of the immune system with macrolide immunosuppressants and (2) modify the induction of transplantation tolerance by macrolide immunosuppressants.
An additional object of the present invention is to provide new analogs of these tricyclomacrolide immunosuppressants which have antagonistic properties. These analogs would find utility in the reversal of the immunosuppressive activity of other FK-506-type immunosuppressive agents and so provide antidotes for overdoses of the immunosuppressants.
An additional object of the present invention is to provide pharmaceutical compositions for administering to a patient one or more of the active macrolide antagonists of the present invention for the modification of treatment with FK-506-type macrolides having immunosuppressive activity.
Still a further object of this invention is to provide a method of modifying the activity of FK-506-type immunosuppressants (which are utilized in controlling graft rejection, autoimmune and chronic inflammatory dieases) by administering a sufficient amount of one or more of the novel macrolide immunosuppressive antagonists in a mammalian species in need of such treatment.
Finally, it is the object of this invention to provide processes for the preparation of the active compounds of the present invention.